Protective apparatus for fluid meters



April 24, 1945. J. w. BEECHER PROTECTIVE APPARATUS FOR FLUID METERSFiled Dec. 22, 1942 Flegl sure existing in the Patented Apr. 24, 1945PROTECTIVE APPARATUS FOR FLUID METERS John Winfred Beeche r, Waterbury,Conn, as-

signor to The Bristol Company, Waterbury, Conn., a corporation ofConnecticut Application December 22, 1942, Serial No. 469,813

14 Claims.

This invention relates to a device for protecting difi'erentialmanometers against abnormal pressure differentials consequent uponfailure or breakage of the conduits or piping systems to which they areconnected, and more especially to the protection of diiferentialmanometers when used in conjunction with orifices or other constrictingdevices for the purpose of determining the rate of flow of a liquidthrough conduits.

In a very large proportion of the installations of diiferentialmanometers for the purpose of determining the pressure developed acrossa constriction in a pipe line or conduit, the static prespiping systemis much greater than the maximum differential pressure corresponding tothe full range of the instrument. When operating conditions are normalthe manometeris not at any time subjected toa differ-- ential pressurein excess of that to which its measuring range is adapted; and, whilethe parts of the instrument may be directly subjected to the staticpressure existing in the line, this appears only as a pressure differingfrom that of the surrounding atmosphere, and is easily resisted by theheavy casing of the instrument. So long as the piping system is intactand the rate of flow through the measuring constriction does not greatlyexceed that for which the instrument is designed, the pressures appliedto the delicate measuring element of the manometer (which may be in thenature of a bellows, a Bourdon spring, or a mercury column) areneutralized, with exception of the difierential due to flow through theconstriction, which diiferential is determined by the manometer and maybe interpreted as a measure of the rate of flow.

In the installation of flow meters it is frequently expedient to locatethe manometer unit at a considerable distance from the main pipe line inwhich the flow is to be determined. The connecting line (generally apair of relatively small and fragile pipes or tubes) is thus likely tobe'sub- 'jeoted to mechanical damage or to unauthorized disconnectionsuch as would be highly improbable in the part of the piping systemimmediately adjacent to the instrument. In the event of such a breakageor accidental disconnection, there is likely to develop either anunbalance pressure in the manometer or a flow of the measured fluidthrough the system in such a manner as to set up pressures which may bedamaging or even destructive to the manometer element.

It is an object of this invention to provide means whereby any flow offluid through the instrument piping system in excess of the slighttransfer necessary for measuring purposes will a'.utomatically bechecked, whereby the manl4 tapped in the wall of ometer element will berelieved of responding to such flow.

It is a further object of the invention to provide means wherebyexcessive pressure across the manometer developing from any causewhatsoever, will be relieved before it has attained a magnitudesuiilcient to damage the measuring element.

In the drawing: Fig. 1 is a diagrammatic representation of a.differential manometer connected across an orifice in a pipe line forthe purpose of measuring flow therein, equipped with a device embodyingthe principles of the invention.

Fig. 2 is a sectional view of one of the elements forming a part of theinvention.

Fig. 3 is a sectional view of another of the elements forming a part ofthe invention.

Referring now to Fig. l of the drawing, the numeral l0 designates aconduit or pipe line adapted to carry a fluid the rate of whose flow isto be determined by means of a diflerential manometer ll connectedacross an orifice member l2 inserted in the conduit Ill. To openings l3and theconduit ill on opposite sides of the orifice member l2 areconnected small pipes or conduits l5 and I6 respectively leading to stopvalves 11 and I8 respectively, whose construction and internalarrangement will hereinafter be set forth, Connected to the stop valvesI! and I8, and normally in communication with the conduits l5 and I6respectively are conduits I 9 and 20, including small orifice pressuresCO1 plates or restrictions 2| and 22 respectively, and

communicating with the manometer ll, whereby any pressure diiferentialbetween the conduits l9 and 20 will be determined by said manometer andindicated in terms of flow through the orifice l2.

The construction and operation of the stop valves l1 and I8 will beunderstood by reference to Fig. 2, which is a sectional view of theformer of these valves. Clamped between a lower and an upper cup shapedmember 23 and 24 respectively is a diaphragm element 25, whereby thereis formed between said members a closed chamber divided into twoportions by said diaphragm element.

Centrally formed on the interior surface of the member 23 is a seat'portion 25 through which communication is established between theportion of the internal chamber beneath the diaphragm 25 and an outlet21 to which is connected the conduit l5. Carried by the diaphragm 25 isa seating member 28 adapted to cooperate with the seat portion 2 .tointerrupt communica- It may nowbe assumed that the conduit Ii tionbetween said chamber and said outlet. The has become disconnectedbetween the stopvalve diaphragm 25 is normally maintained, either by i1and the opening I! in the conduit i0. There its own resiliency or by alight spring 2!,in such will be an immediate tendency for fluid conaposition that the seating member is out of 5 tained in the manometerpipe system to escape engagement with the seat portion 28, allowing fromthe break in the conduit i5, allowing pracfree communication between theinternal chamtically the full static pressure existing in the ber andthe outlet 21. The conduit is communipipe line II to be applied to themanometer ll. cates with the portion of the internal chamber If thiscondition is maintained for any apprein which is located the seatingmember 22, so 0 ciable duration of time, the manometer ii will thatunder normal conditions conduits IO and ii be seriously damaged. If theinstrument be of are in direct communication with each other. theBourdon spring or bellows type the element The portion of the enclosedchamber on the side will be subjected to stresses far in excess of thoseof the diaphragm 25 remote from the seating for 'which it was designed,with the attendant member 28 is provided with an outlet II. Theprobability of its being either ruptured or disstop-valve i8 isstructurally similar to the stoptorted in such a manner as to render theinvalve H, but, by modification of the spring or strument useless. Ifthe manometer be of the of the strength of the enclosed diaphragm, maymercury column type, as indicated in the drawif desired be adjusted toclose at another value ing, the liquid will be blown out of thereservoir of difierential pressure from that which will and theinstrument made inoperative. The actuate the stop-valve IT. The outletll of the function of the protective device to which this stop-valve I1is connected directly to the portion invention is directed is to preventthe attainof the conduit is on the side of the constriction ment ormaintenance of such an abnormal 2i toward the manometer ii; and in asimilar pressure across the manometer element. Upon manner the upperpart of the enclosed chamber the conduit 15 being disconnected and iluid'in the stop valve i8 is connected directly to the escaping therefrom,the flow of said fluid from portion of the conduit 2| on the side of theconthe conduit is through the constriction 2| will striction 22 towardsaid manometer. cause a pressure differential to be developed Connectionbetween the conduits l8 and 2! to across said constriction, whereby thepressure Y-Dass the manometer ii is pr ded y means so applied throughthe opening to the upper of two ba k-pressure valves 33 and 3d, theconpart of the chamber within the valve ll will be struction of whichwill be understood by refergreater than that existing in the lower partof ence to Fig. 3, which is a sectional representathe chamber, and thediaphragm 25 will be tion of the back-pressure valve 3|. The interiorforced downward, bringing the seating member of the valve 34 is formedinto a closed chamber 35 28 into engagement with the seat 26, thuspreseparated into an upper and lower portion by a venting the admissionof substantial quantities partition 35 having therein a valve seat. offluid from the conduit i9 to the conduit I, operating with said valveseat is a. seating memand allowing the pressure in the conduit I! to her38 normally maintainedin engagement with build u to a valueapproximating the static said seat by means of a spring Il'whoseeflective pressure existing in the pipe line it. Thus the f rc m y e aied y 11198-118 f 8 adj manometer element ii will be relieved from thescrew 38. The upper portion 0! the chambe application of extremedifferential pressure, and within the valve ll communicates with theconprotected from serious damage.

duit IS on the side of the constriction 2i toward The substantialstoppage of flow through the the manometer, and the lower portion of the4] constriction 2i will cause the pressures on oppo- ValVe Similarlywith the w t The backsite sides of the diaphragm 25 to tend to becomepressure Valve 3 is c u y Similar to the equalized, but because of theexcess of effective valve ut y be Wasted Open at I area of the diaphragmon the side remote from ferent p essure va e ro t t which said lastthevalve seat 20 over that on the same side of named valve will beactuated. The NW 33 15 I. the valve, there will remain a component ofpresconnectfid in such manner the upper sure scient to overcome theinfluence oi the tion of its internal chamber communicates with spring2g maintain the valve elements m the 5??? and the with the closedengagement, and rendering re-opening of con the stop-valve impossibleuntil the defective con- In considering the the Wave duit is is beenrepaired and a back-pressure device to which the present invention isagain bum up in the same mst g g i g a z As the action of operating thestop-valve ll ed E g i i i I ruires, the se of an appreciable volume ofer g? a 33g 61mm m fluid in order to close the valve, and as there isgfig g Under g; the stop the ibility of slight leakage therethroughvalves n and mu be standing open an that after the valve is closed, theby-pass valve 84 1 provides means of supplying such make-up" the conduitcommunicate 2%: 23, 3 fluid may be necessary to meet these condiai i g iggfl w figg yn cotri tg tions, Without abnoally stressing or otherwise aThe bacbpresam valves 33 and 35, due w damaging the manometer. Theback-pressure the influen e f the 5mm therein, m 31 be valves 33 and itare each adjusted to open at dosed, Thus, the t side, f :g-Ghil. s H a ee very slightly in excess of that reprem be in m u with the mt g sentmathe operating range of the manometer on the corresponding sides of the oii and not sumcient to damage the instrument. n, The n t a pm s n; Uponthe building up of such a pressure due to the flow of fluid in theconduit is th =r h the pe of fluid from the conduit is. h ai orifice l2will thus be applied the i. member 3 within the back-pressure valve 34 nwhich i t n m 1m s n w will be lifted ed the seat 3! due to the pressuremeter in the conventional manner. n from the conduit 20 exceeding thatin the conduit II by an amount greater than that for which the spring I1is adjusted. Fluid will thus be free to pass from the conduit 20 in anupward direction through the back-pressure valve 34 and into the conduitIt, thus oif-setting the tendency for a high differential to developacross the manometer, and also supplying through the constriction 2|such flow as may be permitted by imperfect closing of the stop valve If,any differential pressure caused by such flow through the constriction2| tending to maintain said valve ll pressed against the seat 28.

In a similar manner, should the conduit I become disconnected or open tothe atmosphere,

the escape of fluid therefrom will cause a pressure to be developedacross the constriction 22, with a resultant closure of the stop valveIt; and should leakage through said stop valve continue sufficient tobuild up an undesirable differential pressure across the manometer H,the backpressure valve II will yield and will open, placing conduits IIand 2| in communication, and allowing sufllcient fluid to pass toprevent the development of the undesirable excess pressure across themanometer element.

The terms and expressions which I have em ployed are used as terms ofdescription and not of limitation, and I have no intention, in the useof such terms and expressions, of excluding any equivalents of thefeatures shown and described or portions thereof, but recognize thatvarious modifications are possible within the scope of the inventionclaimed.

I claim:

1. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means,valve means in said connections normally open to provide communicationbetween said conduit means and said manometer. and means cooperatingwith said valve means and responsive to failure of a portion of saidconduit means for causing operation of said valve means to restrictcommunication between said conduit means portion and said manometer.

2. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means,valve means in said connections normally open to provide communicationbetween said conduit means and said manometer and means cooperating withsaid valve means for causing the latter to restrict communicationbetween said manometer and a portion of said conduit means in responseto avelocity of fluid now in excess of a given value in the connectionsbetween said conduit means portion and said manometer.

3. In combination, a pair of conduits adapted to contain fluids atdifferent pressures, a manor-n eter responsive to the difference betweensaid pressures, means connecting said manometer to one of said conduits,a valve in said connecting means, differential-pressure responsive meansfor maintaining said valve normally open to provide communicationbetween said manometer and said conduit, a constriction in saidconnecting means, connections for applying the pressures on oppositesides of said constriction to said differential-pressure means foroperating said valve to flow-restricting position when the pressuredifferential across said constriction exceeds a. predetermined value,and means connecting saidmanometer to the, other of said.

conduits.

4. In combination, a pair of conduits adapted to contain fluids atdifferent pressures, a manometer responsive to the diiference betweensaid pressures, means connecting said manometer to one of said conduits,a valve in said connecting means; a spring maintaining said valvenormally open to provide communication between said conduit and saidmanometer, a diaphragm attached to said valve, a constriction in saidconnecting means, connections for applying the pressures on oppositesides of said constriction to said diaphragm for causing the latter toact in opposition to said spring to operate said valve toflow-restricting position when" the pressure differential across saidconstriction exceeds a predetermined value, and means connecting saidmanometer to the other of said conduits.

5. In combination, a pair of conduits adapted to contain fluids atdifferent pressures, a manometer responsive to the diflerence betweensaid pressures, means connecting said manometer to one of said conduits,means connecting said manometer to the other of said conduits,independently operable valve means in each of said, connecting meansnormally open to establish communication between the correspondingconduit and said manometer, and means responsive to failure of either ofsaid conduits for causing operation of the corresponding valve means torestrict flow therethrough.

6.'In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means,first valve means in said connections normally open to providecommunication between said conduit means and said manometer, normallyclosed second valve means adapted to enable fluid pressure in saidconnections to by-pass said manometer, means coopcrating with said firstvalve means and responsive to failure of a portion of said conduit meansfor causing said valve means to restrictcommunication between saidconduit means portion and said manometer, and means for enabling saidsecond valve means to open when the differential pressure across saidmanometer exceeds a predetermined value. 7

7. In combination, a pair of conduits adapted to contain fluids atdifferent pressures, a manometer'responsive to the difference betweensaid pressures. means connecting said manometer to one of said conduits,a valve in said connecting means; diiferential-pressure responsive meansfor maintaining said valve normally open to provide communicationbetween said manometer and and said conduit, a constriction in saidconnecting" means, connections for applying the pressures on oppositesides of said constriction to said diilerential-pressure means foroperating said valve to flow-restricting position when the pressuredifferential across said constriction exceeds a predetermined value, andmeans connecting said manometer to the other or said condinm, saiddifferential-pressure responsive means oomprising a member subject onopmsite sides to fluid pressures, which member, in the iiow-re strictingposition of said valve, has less efiective area on the side for movingsaid valve away from said position than on the side for maintaining saidvalve in said position.

8. In combination, a pair of conduits adapted opposite sides of saidconstriction .to said dia- I phragm for causing the latter to act inopposition to said spring to operate said valve to flowrestrictingposition when the pressure differential across said constriction exceedsa predetermined value, and means connecting said manometer to the otherof said conduits, said diaphragm, when said valve is in flow-restrictingposition, having less effective area on the side of said spring than onthe opposite side.

9. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means, avalve in said connections, operating means for said valve including amovable pressure-responsive element normally maintaining said valve opento provide communication between said conduit means and said manometer,and connecting means including a constriction for applying pressure tosaid element so that said element is responsive to failure of a portionof said conduit means for shifting said valve to a position restrictingcommunication between said conduit means portion and said manometer,said element, when said valve is in said restricting position havingless effective area on one side than on the other.

10. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means,valve means in said connections normally open to provide communicationbetween said conduit means and said manometer, and means comprisingfixed constrictions in said connections and connections from saidconstrictions, said means cooperating with said valve means andresponsive to failure of a portion of said conduit means for operatingsaid valve means to restrict communication between said conduit meansportion and said manometer.

11. In combination, a pair of conduits adapted to contain fluids atdifferent pressures, a manometer responsive to the difference betweensaid pressures, means connecting said manometer to one of said conduits,means connecting said manometer to the other of said conduits,independ-' ently operable valve means in each of said connecting meansnormally open to establish communication between the correspondingconduit and said manometer, and fixed-orifice means responsive .tofailure of either of said conduits for operating the corresponding valvemeans to restrict flow therethrough.

12. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means,fluid pressure actuated valve means in said connections normally open toprovide communication between said conduit means and said manometer,valve means normally closed and adapted when open to enable fluidpressure in said connections to by-pass said manometer, means comprisingfixed constrictions in said connections and connections from saidconstrictions adapted upon failure of a portion of said conduit means toapply pressure to said pressure-actuated valve means for restrictingcommunication between said conduit means portion and said manometer, andmeans for enabling said second valve means to open when the differentialpressure across said manometer exceeds a predetermined value. 7

13. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means,first valve means in said connections normally open to providecommunication between said conduit means and said manometer, meanscomprising fixed constrictions in said connections and connections fromsaid constrictions cooperating with said valve means and responsive tofailure of a portion of said conduit means for operating said valvemeans to restrict communication between said conduit means portion andsaid manometer, normally closed valve means, and connections to saidnormally closed valve means for opening the same to by-pass saidmanometer and establish communication between said connectionscooperating with the first mentioned valve means.

14. In combination, conduit means adapted to contain fluids at differentpressures, a manometer responsive to the differences between saidpressures, connections between said manometer and said conduit means, avalve in said connections, operating means for said valve including amovable pressure-responsive element normally maintaining said valve opento provide communication between said conduit means and said manometer,and connecting means including a constriction for applying pressure tosaid element so that said element is responsive to failure of a portionof said conduit means for shifting said valve to a 'position restrictingcommunication between said conduit means portion and said manometer,said element, when said valve is in said restricting position havingless effective area on one side than on the other.

JOHN WINFRED BEECHER.

